1. Technical Field
The present invention relates to an offline teaching device which teaches a robot position etc. using a simulation.
2. Description of the Related Art
Articulated robots are widely used on production lines etc. Before using these articulated robots, it is necessary to perform teaching operations on the articulated robots. Performing teaching operations by actually manipulating the articulated robot is inefficient so recently offline teaching operations are common.
Japanese Patent number 4621641 discloses a teaching method in which several pieces of tip information of a robot are set based on the CAD workpiece information, and based on the tip information thus set, the posture of the robot is calculated according to an inverse conversion operation. Further, Japanese Patent number 2868343 discloses an offline teaching method which performs teaching automatically and can improve processing quality when processing an uneven surface of a three dimensional workpiece.
Herein, a laser cutting operation using an articulated robot will be considered. In a laser cutting operation, directly after cutting a workpiece with a laser, the cut portion of the workpiece is cooled by cold water and accordingly the processing quality is improved. Further, by setting the time taken between cutting the workpiece and cooling the workpiece to a constant value, the processing quality can be maintained at a fixed level.
To improve the processing quality or maintain the processing quality at a fixed level in this way, it is necessary that the laser cutting tool and the cooling tool are maintained at a fixed distance and the cooling tool ejects cold water along the trajectory of the laser cutting tool. Therefore, when using an articulated robot to carry out a laser cutting operation, it is necessary to teach the robot position in which cold water is accurately ejected along the trajectory of the laser cutting tool. However, it was not possible to accurately teach such a robot position.
Moreover, if the laser cutting tool and the cooling tool are arranged to have a fixed distance therebetween, when laser machining is performed along a straight path, the time taken between cutting the workpiece and cooling the workpiece can be maintained at a fixed time. However when laser machining is performed along an arced path, the time taken from cutting the workpiece to cooling the workpiece is longer than for a straight path. Therefore, in this case, there was a problem that the processing quality decreased. Note that in machining operations other than the laser cutting operation the same problem would arise.
In view of such circumstances, it is the object of the present invention to provide an offline teaching device which can teach a robot position to accurately eject cold water along the trajectory of a laser cutting tool without the processing quality decreasing even when laser cutting is performed along an arced path.